Entrance switch for conveyors



July 27, 1965 H. s. HARRISON I ENTRANCE SWITCH FOR CONVEYORS FiledSepl'.c 3, 1963 6 Sheets-Sheet 1 o -a-* {I INVENTOR.

Home: 3. HARRISON FIG. 2 BY 41 m K W A TTORN E Y5 y 27, 1965 H. s.HARRISON 3,196,80

ENTRANCE SWITCH FOR CONVEYORS Filed Sept. 3, 1963 6 Sheets-Sheet 2 II xl 43 i I I. I i

FIG-4 INVENTOR. HOMER 5. HARRISON BY M W x W ATTORNEYS July 27, 1965 H.5. HARRISON ENTRANCE SWITCH FOR CONVEYORS Filed Sept. 5, 1963' sShets-Sheet s INVENTOR. Homee 5. HARRISON BY W x M ATTORNEYS July 27,1965 H. s. HARRISON ENTRANCE SWITCH FOR CONVEYORS 6 Sheets-Sheet 4 FiledSept. 3, 1963 N m0 m5 H S M o H v/v BY} ATTORNEYS J y 1965 H. s.HARRISON 3,

ENTRANCE swrrcn FOR CONVEYORS Filed Sept. 3, less 6 Sheets$heet 5INVENTOR.

HOMER S. HARRISON 1 will? WM- u Q U u ATTORNEYS July 27; 1965 H. s.HARRISON ENTRANCE SWITCH FOR CONVEYORS 6 Sheets-Sheet 6 Filed Sept. 5,1965 4----'mwm INVENTOR. Home-e S. HARRISON ATTORNEYS United StatesPatent 3,196,804 ENTRANGE SWETCH FQR (IONVEYORS Homer S. Harrison,Detroit, Mich, assignor to Mechanicai Handling Systems, Inc., Detroit,Mich, a corporation of Michigan Filed Sept. 3, 1963, Ser. No. 3%,985 33Claims. (Cl. 194-96) This invention relates to conveyors such as powerand free conveyors.

In conveyor systems wherein a carrier or trolley unit is movable along atrack, and wherein main and branch tracks are provided, it is essentialto provide for a positive movement of the trolley unit into register asit moves from the branch track to the main track.

It is an object of this invention to provide a novel entrance switch forpermitting the controlled movement of a trolley unit from a branch trackto a main track.

It is a further object of the invention to provide such an entranceswitch wherein the movement of the trolley unit is positively controlledfrom a position at rest, accelerated without shock into movement andregistry with a transfer conveyor which then positively transfers thecarrier unit to the main track.

It is a further object of the invention to provide such an entranceswitch that utilizes a minimum number of parts, is relatively easy tomaintain and is reliable.

In the drawings:

FIG. 1 is a fragmentary plan view of a conveyor system embodying theinvention.

FIG. 2 is a fragmentary view on an enlarged scale of a portion of FIG. 1showing the movement of a trolley unit from the branch track to the maintrack.

FIG. 3 is a fragmentary sectional view taken along the line 33 in FIG.2.

FIG. 4 is a fragmentary sectional view taken along the line 4-4 in FIG.2.

FIG. 5 is a fragmentary elevational view of a portion of the track ofthe conveyor system.

FIG. 6 is a fragmentary sectional view taken along the line 6-6 in FIG.5.

FIG. 7 is a fragmentary plan view of the entrance switch embodying theinvention, parts being broken away.

FIG. 8 is a fragmentary sectional view taken along the line 8-8 in FIG.7.

FIG. 9 is a fragmentary plan view of a portion of the switch shown inFIG. 7 in a different operative position.

FIG. 10 is a fragmentary elevational View in the direction of the arrow16 in FIG. 7.

FIG. 11 is a fragmentary elevational view of a portion of the apparatusshown in FIG. 10 in a different operative position.

FIG. 12 is a fragmentary plan view similar to FIG. 7 showing the partsin a different operative position.

FIG. 13 is a diagrammatic plan view of a portion of the entrance switch.

FIG. 14 is a diagrammatic view similar to FIG. 13 showing the parts inthe different operative position.

Referring to the drawings, the invention is shown and described inconnection with a power and free conveyor system of conventionalconstruction comprising a main track formed by spaced channels 21, 22for supporting carrier or trolley units 23 for movement therealong(FIGS. 5, 6). Each trolley unit 23 includes rollers 24 which ride on theupper surfaces of the channels 21,22 and a guide roller 25 which ridesbetween the channels 21, 22 to guide the trolley unit. The trolley units23 are moved along the track by an endless power chain 26 having pushers27 at longitudinally spaced points thereon for engaging spring loadeddogs 28 on the carrier units 23 (FIG. 3). The chain 26 is suspended atlongitudi- 3,336,364- Patented .Iuly 27, 1965 nally spaced points from abeam 30' by hanger units 3%).

As shown in FIGS. 1 and 2, a branch track 41 comprising spaced channels41a, 41b has a portion thereof which converges into the main track 20. Atransfer conveyor 42 comprising an endless chain 43 is mounted on aframe 46 positioned along converging portions of the main track 20 andbranch track 41. Transfer conveyor 43 includes lugs 44 which mesh withthe chain 26 of the main conveyor and thereby power the transferconveyor 42 (FIG. 2). In addition, the transfer conveyor includestransfer lugs 45 at longitudinally spaced points thereon which areadapted to engage between the dogs 28 of trolley units to transfer thetrolley units from the branch track 41 to the main track 20, aspresently described.

Referring to FIGS. 1 and 2, the frame 46 which supports the transferchain 42 has a portion thereof 47 which converges with the branch track41. The entrance control switch is positioned in this area.

As shown in FIGS. 1 and 7, a pivot arm 48 has one end thereof pivoted toa crossbar 49 and the other end thereof being bent downwardly andsupporting a pusher dog 50. The pusher dog is movable from a positionshown in FIG. 1 in a swinging motion along the path of the branch track41 and thereafter laterally outwardly of the path of the track. In thefirst position, the dog 56 is in position to engage between the dogs 28of a trolley unit and stop the trolley unit in position in advance ofthe transfer conveyor 42. In accordance with the invention, mechanism isprovided for positively moving a trolley unit 23 by means of the pusherdogs 50 from this position into a position where it is positivelyengaged and picked up by a transfer lug 45 on the transfer conveyor 42.This positive movement of the trolley unit 23 occurs only if a transferlug 45 on the transfer conveyor 42 is in proper position and only ifthere is an empty space on the main conveyor.

As shown in FIG. 7, an accelerator arm 51 has one end thereof pivoted tocross bar 49 at a point in line transversely with the pivot of arm 48. Alink 52 has one end thereof pivoted to the accelerator arm 51 and theother end thereof pivoted on the swinging end of pivot arm 48.

A latch 56 is pivoted to arm 51 at the point of pivot of arm 51 and link52 and has a notch 57 which engages a fixed lug 58 on the transferconveyor track 46. An accelerator dog lever 53 is pivoted to latch 56.Dog lever 53 includes a notch 54 which is adapted to be moved intoposition as shown in dotted lines in FIG. 7, for engagement by theupstanding portion of transfer lug 45.

Accelerator arm 51 has an opening 60 therein through which end of pivotpin 59, which pivots the accelerator dog 53 to the latch 56, extends(FIG. 8). The opening 60 has a larger diameter than the bushing 61 thatis threaded on the pin 59 so there i some permissible movement of thelatch 56 relative to the accelerator arm 51.

Accelerator dog 53 includes an upstanding pin 62 at its other end whichis adapted to be engaged by a release lever 63 to prevent thecounterclockwise swinging movement of the accelerator dog 53. Releaselever 63 includes a vertical downwardly extending portion 64 (FIG. 10)which is adapted to be engaged by the rearmost dog 28 on a trolley unit23 to swing the release lever 63 upwardly. This is achieved when atrolley unit 23 is moved into position on the pusher dog 50, eithermanually or in some other fashion. A tension spring 65 extends betweenthe accelerator dog 53 and an arm 66 on the frame. When the trolley unit23 is present on the pusher dog 50, as having been moved by hand or abranch conveyor, the release lever 63 is rotated counterclockwise byengagement of the rear dog 28 with arm 64 to swing the release lever 63out of engagement with the pin 62, permitting the spring 65 to swing theaccelerator dog 53 counterclockwise, as shown in FIG. 7, into positionwhere the notch portion 54 can be engaged by the upright portion of thelug 45 on the transfer conveyor 42.

The amount of swinging movement of the accelerator dog 53 is limited byengagement of a lug 67 with a lug 68 on the accelerator arm 51. If atrolley unit 23 is in position on the pusher dog 50 and a transfer lug45 approaches, it engages the notched portion 54 of the accelerator dog53 and begins to move the accelerator dog 53 in a clockwise fashion.During the initial movement, the pin 59 rotates the latch 56 clockwiserelative to the accelerator arm 51 due to the space between the opening60 and the bushing 61, releasing the engagement of the notch 57 with thelug 58. Continued movement of the transfer conveyor 42 swings the pusherdog 50 and accelerates it without shock along the path of the conveyorand thereafter laterally outwardly to the dotted line position shown inFIG. 7.

The timing movement of the pusher dog 50 and transfer dog 45 is suchthat there is a positive control of the trolley unit. This is showndiagrammatically in FIGS. 13 and 14 wherein the pusher dog 50 is notmoved out of engagement with the dogs 28 of the trolley unit 23 untilthe transfer lug 45 is in engagement. In this manner, the trolley unitis accelerated from the at rest position and is moved along positivelyuntil the transfer conveyor lug 45 engages therewith.

The transfer conveyor 42 then carries the trolley unit 23 along thebranch track 41 into position as shown in FIG. 2 for engagement by apusher dog 27 on the main conveyor with the carrier unit. Therelationship of the transfer dog 45 and pusher dog 27 is such that thecontrol by the transfer conveyor dog 45 is not released until the pusherdog 27 on the main conveyor is in register with and picks up the trolleyunit 23. As the pusher dog continues its movement and swings laterallyout of engagement with the dog 28 of trolley unit 23, pin 62 engages afixed cam surface 76 which swings accelerator dog 53 clockwise torelease accelerator dog 53 from engagement with upstanding portion 55 oftransfer lug 45. This permits spring 65 to return the dog 50 to itsoriginal position wherein latch 56 engages lug 58 so that the entranceswitch is in position for controlling the movement of a succeedingtrolley 23.

In order to prevent transfer of a trolley unit 23 when a space is filledon the main track, means are provided for preventing the release of thepusher dog 50. As shown in FIGS. 1, 7 and 9, this comprises a controllever 70 which is pivoted along the main track and has one end thereofadapted to project into the path of the trolley units. Thus, if atrolley unit is on the main track, the lever 70 will be swung clockwiseas viewed in FIG. 1. The other end of the lever 7 is connected by a link72 and extends to a bracket 73. A spring 74 yieldingly urges the link 72into the bracket, thereby urging the lever 70 in a counterclockwiserelationship, as viewed in FIG. 1.

If a trolley unit is present and the lever 70 is swunk clockwise, thelink 72 is moved upwardly, as viewed, to a position such as shown inFIG. 9, moving a projection 75 into the path of the pin 62 on theaccelerator dog 53 and thereby preventing the accelerator dog fromswinging to the dotted line position even though the accelerator dog isreleased by the presence of the trolley unit 23 on the pusher dog 50. Inthis manner, the transfer of a trolley unit to a filled position on themain track is prevented.

I claim: 1. In a conveyor system, the combination comprising a maintrack, a plurality of trolley units adapted to be moved along the maintrack, a main conveyor adapted to engage said trolley units and movethem along the main track, a branch track for guiding similar trolleyunits, said main track and branch track having portions thereofconverging to guide the trolley units from the branch track to the maintrack, an endless transfer conveyor positioned adjacent said main trackand deriving power directly therefrom,

said transfer conveyor having portions thereof positioned and travelingadjacent the converging portion of said branch track,

means on said transfer conveyor for engaging a trolley unit on thebranch track,

and an entrance switch for controlling the movement of the trolley unitsinto position for engagement by said transfer conveyor,

said entrance switch comprising a pusher dog adapted to engage a trolleyunit and move it in the direction of the branch track toward the maintrack,

and means responsive to the movement of said means on the transferconveyor into position for engagement with a trolley unit on the branchtrack for moving and accelerating the pusher dog to thereby move thetrolley unit positively in position for engagement by said means on thetransfer conveyor.

2. The combination setforth in claim 1 including means responsive tomovement of a trolley unit on the main conveyor indicating a filledspace on the main conveyor for disabling the entrance switch andpreventing the pusher dog from being moved and accelerated.

3. In a conveyor system, the combination comprising a main track,

a plurality of trolley units adapted to be moved along the main track,

a main conveyor adapted to engage said trolley units and move them alongthe main track,

a branch track for guiding similar trolley units,

said main track and branch track having portions thereof converging toguide the trolley units from the branch track to the main track, anendless transfer conveyor positioned adjacent said main track andderiving power directly therefrom,

said transfer conveyor having portions thereof positioned and travelingadjacent the converging ortion of said branch track,

means on said transfer conveyor for engaging a trolley unit on thebranch track,

and an entrance switch for controlling the movement of a trolley unitfrom the branch conveyor into position for engagement by said means onthe transfer conveyor comprising a pusher dog, means for mounting thepusher dog for movement from a first position in the path of a trolleyunit on the branch track along said track and thereafter laterally outof the path of said track to disengage the trolley unit, means forholding the pusher dog in said first position, and means responsive tothe movement of said means on the transfer conveyor into position forengaging the trolley unit being held on the branch conveyor,

said last-mentioned means releasing said pusher dog and accelerating andmoving said pusher dog along said path along the branch track andthereafter laterally out of the path of said track,

thereby moving said trolley units into position to be engaged by saidmeans on said transfer conveyor before the pusher dog is moved laterallyout of engagement with the trolley unit.

4. The combination set forth in claim 3 including means responsive tothe movement of a trolley on the main conveyor indicating a filled spaceon the main conveyor for preventing the release of the pusher dogpositioned adjacent the branch conveyor.

5. In a conveyor system, the combination comprising a main track,

a plurality of trolley units adapted to be moved along the main track,

a main conveyor adapted to engage said trolley units and move them alongthe main track,

a branch track for guiding similar trolley units,

said main track and branch track having portions thereof converging toguide the trolley units from the branch track to the main track,

an endless transfer conveyor positioned adjacent said main track andderiving power directly therefrom,

said transfer conveyor having portions thereof positioned and travelingadjacent the converging portion of said branch track,

means on said transfer conveyor for engaging a trolley unit on thebranch track,

and an entrance switch for controlling the movement of a trolley unitfrom the branch conveyor into position for engagement by said means onthe transfer conveyor comprising a pusher dog,

means for mounting the pusher dog for swinging movement from a firstposition in the path of a trolley unit on the branch track along saidtrack and thereafter laterally out of the path of said track todisengage the trolley unit,

means for holding the pusher dog in said first position,

and means responsive to the movement of said means on the transferconveyor into position for engaging the trolley unit being held on thebranch conveyor to release said pusher dog and accelerate and move saidpusher dog along said path along the branch track and thereafterlaterally out of the track,

thereby moving said trolley unit into position to be engaged by saidmeans on said transfer conveyor before the pusher dog is moved laterallyout of engagement with the trolley unit.

6. In a conveyor system, the combination comprising a main track,

a plurality of trolley units adapted to be moved along the main track,

a main conveyor adapted to en age said trolley units and move them alongthe main track,

a branch track for guiding similar trolley units,

said main track and branch track having portions there of converging toguide the trolley units from the branch track to the main track,

an endless transfer conveyor positioned adjacent said main track andderiving power directly therefrom, said transfer conveyor havingportions thereof positioned and traveling adjacent the convergingportion of said branch track,

means on said transfer conveyor for engaging a trolley unit on thebranch track,

and an entrance switch for controlling the movement of a trolley unitfrom the branch conveyor into position for engagement by said means onthe transfer conveyor comprising a pusher dog,

means for mounting the pusher dog for swinging movement from a firstposition in the path of a trolley unit on the branch track along saidtrack and there after laterally out of the path of said track to disengage the trolley unit,

means for holding the pusher dog in the first position,

and means responsive to the movement of said means on the transferconveyor into position for engaging the trolley unit being held on thebranch conveyor to release said pusher dog and engage said pusher dogwith said transfer conveyor to accelerate and swing said pusher dogalong said path along the branch track and thereafter laterally out ofthe track,

thereby moving said trolley unit into position to be engaged by saidmeans on said transfer conveyor before the pusher dog is moved laterallyout of engagement with the trolley.

7. In a conveyor system, the combination comprising a main track,

a plurality of trolley units adapted to be moved along the main track,

a main conveyor adapted to engage said trolley units and move them alongthe main track,

a branch track for guiding similar trolley units,

said main track and branch track having portions thereof converging toguide the trolley units from the branch track to the main track,

a frame,

an endless transfer conveyor positioned on saidframe adjacent said maintrack and deriving power directly therefrom,

said transfer conveyor having portions thereof positioned and travelingadjacent the converging portion of said branch track,

said transfer conveyor having transfer lugs thereon for engaging trolleyunits and moving them along said branch track,

and an entrance switch mechanism for contolling the movement of atrolley unit into said converging portion of the branch track which isadjacent the transfer conveyor for engagement by a transfer lug on thetransfer conveyor which comprises a pivot arm mounted for swingingmovement adjacent the converging portion of the transfer conveyor andbranch track,

a pusher dog mounted on the end of said pivot arm and adapted to movefrom a first position in register with the path of the branch trackalong the branch track and thereafter laterally out of the path of thebranch track,

an accelerator arm pivoted for swinging movement adjacent the convergingportion of the transfer conveyor and the branch track,

interconnecting means between said pivot arm and said accelerator arm,

means for locking said pusher dog in said first position,

and means responsive to the movement of a lug on said transfer conveyorfor releasing said locking means and engaging said accelerator arm withsaid transfer conveyor to accelerate and swing said pusher dog.

8. In a conveyor system, the combination comprising a main track,

a plurality of trolley units adapted to be moved along the main track,

a main conveyor adapted to engage said trolley units and move them alongthe main track,

a branch track for guiding similar trolley units,

said main track and branch track having portions thereof converging toguide the trolley units from the branch track to the main track,

a frame,

an endless transfer conveyor positioned on said frame adjacent said maintrack and deriving power directly therefrom,

said transfer conveyor having portions thereof positioned and travelingadjacent the converging portion of said branch track,

said transfer conveyor having transfer lugs thereon for engaging trolleyunits and moving them along said branch track,

and an entrance switch mechanism for controlling the movement of atrolley unit into said converging portion of the branch track which isadjacent the transfer conveyor for engagement by a transfer lug on thetransfer conveyor which comprises a pivot arm mounted for swingingmovement adjacent the converging portion of the transfer conveyor andbranch track,

a pusher dog mounted on the end of said pivot arm and adapted to movefrom a first position in register with the path of the branch trackalong the branch track and thereafter laterally of the path 'of thebranch track,

an accelerator arm pivoted for swinging movement adjacent the convergingportion of the transfer conveyor and the branch track,

a linkvpivoted to said accelerator arm and said pivot arm,

an accelerator dog pivoted to said accelerator arm and adapted to beengaged by a transfer lug on said transfer conveyor for moving saidaccelerator dog and in turn, said accelerator arm to accelerate andswing said pivot arm with said transfer conveyor,

and latch means between said frame and said accelerator arm forpreventing movement of said accelerator arm and, in turn, said pivotarm.

9. The combination set forth in claim 8 including means responsive tothe presence of a trolley unit at said first position for moving saidaccelerator dog in position to be engaged by said transfer conveyor.

10. The combination set forth in claim 8 including means responsive tomovement of a trolley unit along the main conveyor indicating a filledspace on the main conveyor for preventing said accelerator dog frommovement into position to be engaged by said transfer conveyor.

11. The combination set forth in claim 8 including means in the path ofsaid accelerator dog as it moves along when released for disengagingsaid dog from said transfer conveyor to permit the return of saidaccelerator arm, pivot arm, pusher dog and accelerator dog to theiroriginal positions.

12. The combination set forth in claim 8 including spring means forreturning said accelerator arm, pivot arm, pusher dog and acceleratordog to their original positions.

13. In a conveyor system, the combination comprising a main track,

a plurality of trolley units adapted to be moved along the main track,

a main conveyor adapted to engage said trolley units and move them alongthe main track,

a branch track for guiding similar trolley units,

said main track and branch track having portions thereof converging toguide the trolley units from the branch track to the main track,

a frame,

an endless transfer conveyor positioned on said frame adjacent said maintrack and deriving power directly therefrom,

said transfer conveyor having portions thereof positioned and travelingadjacent the converging portion of said branch track,

said transfer conveyor having transfer lugs thereon for engaging trolleyunits and moving them along said branch track,

and an entrance switch mechanism for controlling the movement of atrolley unit into said converging portion of the branch track which isadjacent the transfer conveyor for engagement by a transfer lug on thetransfer conveyor which comprises a pivot arm mounted for swingingmovement adjacent the converging portion of the transfer conveyor andbranch track,

a pusher dog mounted on the end of said pivot arm and adapted to movefrom a first position in register with the path of the branch trackalong the branch track and thereafter laterally of the path of thebranch track,

an accelerator arm pivoted for swinging movement adjacent the convergingportion of the transfer conveyor and the branch track,

a link pivoted to said accelerator arm and said pivot arm,

a latch pivoted to said accelerator arm and adapted to engage said frameto lock said arm,

an accelerator dog pivoted to said latch and adapted to be engaged by atransfer lug on said transfer conveyor for moving said accelerator dogand, in turn, said accelerator arm to accelerate and swing said pivotarm with said transfer conveyor.

14. The combination set forth in claim 13 including lost motion meansbetween said latch and said acceleration arm to permit disengagement ofsaid latch.

15. The combination set forth in claim 14 including means responsive tothe presence of a trolley unit at said first position for moving saidaccelerator dog in position to be engaged by said transfer conveyor.

16. The combination set forth in claim 13 including means responsive tomovement of a trolley along the main conveyor indicating a filled spaceon the main conveyor for preventing said accelerator dog from movementinto position to be engaged by said transfer conveyor.

17. The combination set forth in claim 13 including means in the path ofsaid accelerator dog as it moves along and, when released, fordisengaging said dog from said transfer conveyor to permit the return ofsaid accelerator arm, pivot arm, pusher dog and accelerator dog to theiroriginal position.

18. The combination set forth in claim 13 including spring means forreturning said accelerator arm, pivot arm, pusher dog and acceleratordog to their original position.

19. In an entrance switch for a conveyor system comprising a main track,a plurality of trolley units adapted to be moved along the main track, amain conveyor adapted to engage said trolley units and move them alongthe main track, a branch track for guiding similar trolley units, saidmain track and branch track having portions thereof converging to guidethe trolley units from the branch track to the main track, thecombination comprising,

an endless transfer conveyor adapted to be positioned adjacent said maintrack and deriving power directly therefrom,

means on said transfer conveyor for engaging a trolley unit on thebranch track,

a pusher dog adapted to engage a trolley unit and move it in thedirection of the branch track toward the main track,

and means responsive to the movement of said means on the transferconveyor into position for engagement with a trolley unit on the branchtrack for moving and accelerating the pusher dog to thereby move atrolley unit positively in position for engagement by the means on thetransfer conveyor.

20. The combination set forth in claim 19 including means adapted to bepositioned along the main track responsive to movement of a trolley uniton the main conveyor indicating a filled space on the main conveyor fordisabling the entrance switch and preventing the pusher dog from beingmoved and accelerated.

21. In an entrance switch for a conveyor system comprising a main track,a plurality of trolley units adapted to be moved along the main track, amain conveyor adapted to engage said trolley units and move them alongthe main track, a branch track for guiding similar trolley units, saidmain track and branch track having portions thereof converging to guidethe trolley units from the branch track'to the main track, thecombination comprising an endless transfer conveyor adapted to bepositioned adjacent said main track and deriving power directlytherefrom,

means on said transfer conveyor for engaging a trolley unit on thebranch track,

a pusher dog,

means for mounting the pusher dog for movement from a first position inthe path of a trolley unit on the branch track along said track andthereafter laterally out of the path of said track to disengage thetrolley unit,

means for holding the pusher dog in said first position,

and means responsive to the movement of said means on the transferconveyor into position for engaging the trolley unit being held on thebranch conveyor,

said last-mentioned means releasing said pusher dog and accelerating andmoving said pusher dog along said path along the branch track andthereafter laterally out of the path of said track,

thereby moving said trolley units into position to be engaged by saidmeans on said transfer conveyor before the pusher dog is moved laterallyout of engagement with the trolley unit.

22. In an entrance switch for a conveyor system comprising a main track,a plurality of trolley units adapted to be moved along the main track, amain conveyor adapted to engage said trolley units and move them alongthe main track, a branch track for guiding similar trolley units, saidmain track and branch track having portions thereof converging to guidethe trolley units from the branch track to the main track, thecombination comprising an endless transfer conveyor adapted to bepositioned adjacent said main track and deriving power directlytherefrom,

means on said transfer conveyor for engaging a trolley unit on thebranch track,

a pusher dog,

means for mounting the pusher dog for swinging movement from a firstposition in the path of a trolley unit on the branch track along saidtrack and thereafter laterally outof the path of said track to disengagethe trolley unit,

means for holding the pusher dog in the first position,

and means responsive to the movement of said means on the transferconveyor into position for engaging the trolley unit being held on thebranch conveyor for releasing said pusher dog and accelerating andmoving said pusher dog along said path along the branch track andthereafter laterally out of the track,

thereby moving said trolley units into position to be engaged by saidmeans on said transfer conveyor befor the pusher dog is moved laterallyout of engagement with the trolley.

23. In an entrance switch for a conveyor system comprising a main track,a main conveyor adapted to engage said trolley units and move them alongthe main track, a branch track for guiding similar trolley units, saidmain track and branch track having portions thereof converging to guidethe trolley units from the branch track to the main track, thecombination comprising a frame,

an endless transfer conveyor positioned on said frame adjacent said maintrack and deriving power directly therefrom,

said transfer conveyor having transfer lugs thereon for engaging trolleyunits .and moving them along said branch track,

a pivot arm mounted for swinging movement adjacent the convergingportion of the transfer conveyor and branch track,

a pusher dog mounted on the end of said pivot arm and adapted to movefrom a first position in register with the path of the branch trackalong the branch track and therafter laterally of the path of the branchtrack,

an accelerator arm pivoted for swinging movement adjacent the convergingportion of the transfer conveyor and the branch track,

interconnecting means between said pivot arm and said accelerator arm,

means for locking said pusher dog in said first position,

and means responsive to the movement of a lug on said transfer conveyorfor releasing said locking means and engaging said accelerator arm withsaid transfer conveyor to accelerate and swing said pusher dog.

24. In an entrance switch for a conveyor system comprising a main track,a plurality of trolley units adapted to be moved along the main track, amain conveyor adapted to engage said trolley units and move them alongthe main track, a branch track for guiding similar trolley units, saidmain track and branch track having portions thereof converging to guidethe trolley units from the branch track to the main track, thecombination comprising a frame,

an endless transfer conveyor positioned on said frame adjacent said maintrack and deriving power directly therefrom,

said transfer conveyor having transfer lugs thereon for engaging trolleyunits and moving them along said branch track,

a pivot arm mounted for swinging movement adjacent the convergingportion of the transfer conveyor and branch track,

a pusher dog mounted on the end of said pivot arm and adapted to movefrom a first position in register with the path of the branch trackalong the branch track and thereafter laterally of the path of thebranch track,

an accelerator arm pivoted for swinging movement adjacent the convergingportion of the transfer conveyor and the branch track,

a link pivoted to said accelerator arm and said pivot arm,

an accelerator dog pivoted to said accelerator arm and adapted to beengaged by a transfer lug on said transfer conveyor for moving saidaccelerator dog and, in turn, said accelerator arm to accelerate andswing said pivot arm with said transfer conveyor,

latch means between said frame and said accelerator arm for preventingmovement of said accelerator arm and, in turn, said pivot arm.

25. The combination set forth in claim 24 including means responsive tothe presence of a trolley at said first position for moving saidaccelerator dog in position to be engaged by said transfer conveyor.

26. The combination set forth in claim 24 including means adapted to bepositioned along the main conveyor responsive to movement of a trolleyalong the main conveyor indicating a filled space on the main conveyorfor preventing said accelerator dog from movement into position to beengaged by said transfer conveyor.

27. The combination set forth in claim 24 including means in the path ofsaid accelerator dog as it moves along when released for disengagingsaid dog from said transfer conveyor to permit the return of saidaccelerator arm, pivot arm, pusher dog and accelerator dog to theiroriginal position.

28. The combination set forth in claim 24 including spring means forreturning said accelerator arm, pivot arm, pusher dog and acceleratordog to their original position.

29. In an entrance switch for a conveyor system comprising a main track,a plurality of trolley units adapted to be moved along the main track, amain conveyor adapted to engage said trolley units and move them alongthe main track, a branch track for guiding similar trolley units, saidmain track and branch track having portions thereof converging to guidethe trolley units from the branch track to the main track, thecombination comprising,

a frame,

an endless transfer conveyor positioned on said frame adjacent said maintrack and deriving power directly therefrom,

said transfer conveyor having transfer lugs thereon for engaging trolleyunits and moving them along said branch track,

a pivot arm mounted for swinging movement adjacent the convergingportion of the transfer conveyor and branch track,

a pusher dog mounted on the end of said pivot arm and adapted to movefrom a first position in register with the path of the branch trackalong the branch track and thereafter laterally of the path of thebranch track,

an accelerator arm pivoted for swinging movement adjacent the convergingportion of the transfer conveyor and the branch track,

a link pivoted to said accelerator arm and said pivot arm,

a latch pivoted to said accelerator arm and adapted to engage said frameto lock said arm,

an accelerator dog pivoted to said latch and adapted to be engaged by atransfer lug on said transfer conveyor for moving said accelerator dogand, in turn, said accelerator arm to accelerate and swing said pivotarm with said transfer conveyor.

30. The combination set forth in claim 29 including lost motion meansbetween said latch and said accelerator arm to permit disengagement ofsaid latch.

31, The combination set forth in claim 29 including means responsive tothe presence of a trolley at said first position for moving saidaccelerator dog in position to be engaged by said transfer conveyor.

32. The combination set forth in claim 29 including means in the path ofsaid accelerator dog as it moves along when released for disengagingsaid dog from said transfer conveyor to permit the return of saidaccelerator arm, pivot arm, pusher dog and accelerator dog to theiroriginal position.

33. The combination set forth in claim 29 including spring means forreturning said accelerator arm, pivot arm, pusher dog and acceleratordog to their original position.

References Cited by the Examiner UNITED STATES PATENTS 2,868,138 1/59Bishop et al. 104--88 2,868,139 1/59 Klamp 104-88 3,044,415 7/62 Dehne104172 3,056,360 10/62 Burrneister et al 104-96 EUGENE G. BOTZ, PrimaryExaminer.

ARTHUR L, LA POINT, Examiner.

1. IN A CONVEYOR SYSTEM, THE COMBINATION COMPRISING A MAIN TRACK, APLURALITY OF TROLLEY UNITS ADAPTED TO BE MOVED ALONG THE MAIN TRACK, AMAIN CONVEYOR ADAPTED TO ENGAGE SAID TROLLEY UNITS AND MOVE THEM ALONGTHE MAIN TRACK, A BRANCH TRACK FOR GUIDING SIMILAR TROLLEY UNITS, SAIDMAIN TRACK AND BRANCH TRACK HAVING PORTIONS THEREOF CONVERGING TO GUIDETHE TROLLEY UNITS FROM THE BRANCH TRACK TO THE MAIN TRACK, AN ENDLESSTRANSFER CONVEYOR POSITIONED ADJACENT SAID MAIN TRACK AND DERIVING POWERDIRECTLY THEREFROM, SAID TRANSFER CONVEYOR HAVING PORTIONS THEREOFPOSITIONED AND TRAVELING ADJACENT THE CONVERGING PORTION OF SAID BRANCHTRACK, MEANS ON SAID TRANSFER CONVEYOR FOR ENGAGING A TROLLEY UNIT ONTHE BRANCH TRACK, AND AN ENTRANCE SWITCH FOR CONTROLLING THE MOVEMENT OFTHE TROLLEY UNITS INTO POSITION FOR ENGAGEMENT BY SAID TRANSFER SWITCH,SAID ENTRANCE SWITCH COMPRISING A PUSHER DOG ADAPTED TO ENGAGE A TROLLEYUNIT AND MOVE IT IN THE DIRECTION OF THE BRANCH TRACK TOWARD THE MAINTRACK, AND MEANS RESPONSIVE TO THE MOVEMENT OF SAID MEANS ON THETRANSFER CONVEYOR INTO POSITION FOR ENGAGEMENT WITH A TROLLEY UNIT ONTHE BRANCH TRACK FOR MOVING AND ACCELERATING THE PUSHER DOG TO THEREBYMOVE THE TROLLEY UNIT POSITIVELY IN POSITION FOR ENGAGEMENT BY SAIDMEANS ON THE TRANSFER CONVEYOR.